This invention relates to a process for the catalytic conversion of methanol into hydrogen and carbon monoxide.
There are increasing demands for hydrogen and carbon monoxide in many fields and methanol is now an important starting material therefor in that it can give hydrogen and carbon monoxide through catalytic decomposition. In an internal combustion engine, the waste heat generated therefrom can be utilized for the catalytic conversion of methanol into hydrogen and carbon monoxide, the mixed gas product being introduced into the engine as at least a part of the fuel. This method has advantages not only from an economic point of view but also from the standpoint of preventing pollution since the discharge of nitrogen oxides and carbon monoxide may be significantly reduced.
Catalytic conversion of methanol is also utilized in a fuel cell, in which an oxygen-containing gas is supplied to the anode and a fuel, preferably hydrogen, is supplied to the cathode. The reaction between the anode and cathode can produce an electrical energy. The hydrogen may be produced from methanol. Thus, methanol is catalytically converted into hydrogen and carbon monoxide, the latter being further reacted with water to yield hydrogen and carbon dioxide by water gas reaction. The hydrogen obtained in the two-stage process is separated from carbon dioxide for introduction to the cathode.
In addition, hydrogen and carbon monoxide are used in a wide variety of chemical plants. For example, hydrogen is utilized for hydrogenation of organic compounds, hydrotreatment of heavy hydrocarbon oils, etc., and carbon monoxide is utilized for the production of carbonyl group-containing organic compounds.
There is, therefore, a great demand for an effective process capable of converting methanol into hydrogen and carbon monoxide. A process is proposed in which a catalyst containing nickel, lanthanum and ruthenium supported on silica gel is used. Although the catalyst can exhibit a relatively high activity for the decomposition of methanol at an initial stage, the catalytic activity is gradually lowered as the reaction at about 300.degree. C. proceeds and the catalyst is considerably deteriorated after about several hours. A process is also known wherein a catalyst having copper and/or nickel supported on silica gel is used. This catalyst, however, is poor in resistance to heat and, moreover, is defective because with it undesirable by-products such as water and methane are formed at about 400.degree. C. or more. The term "formation of by-products" herein and hereinafter means the case where compounds other than methanol, hydrogen and carbon monoxide are contained in the reaction product in an amount of 10 vol % or more. The formation of by-products requires an additional step for the removal thereof and is not acceptable in practice.